1. Field of the Invention
The present invention relates to an apparatus employing an inkjet recording method, and more particularly to a recording apparatus for use in a printer for ejecting droplets from a nozzle to a recording medium.
2. Description of the Related Art
There has recently been a growing interest in non-impact printers, because noise while recording is extremely small to such a degree that it can be neglected. Particularly, inkjet printers are extremely effective in that they are structurally simple and that they can perform high-speed recording directly onto ordinary medium.
Inkjet printers fall into three broad categories: continuous type, on-demand (or impulse) type and electrostatic type. Among these types, the on-demand inkjet printer is provided with a lot of piezoelectric actuators which are selectively driven to eject ink droplets. Since a piezoelectric actuator ejects ink droplets on demand, it is possible to avoid needless ink consumption. Further, since the on-demand inkjet printer is structurally simple, it is expected to be widely used.
Recently, a color printer has been commercially available and the quality of color print is becoming increasingly higher. For a color inkjet head for use in such a color printer, it is very important to eliminate bleeding due to a combination of black and color nozzles.
In Japanese Patent Unexamined Publication No. 7-205454, an inkjet printer has been disclosed in which, to eliminate the bleeding when printing, an array of black nozzles is provided at a distance from other arrays of color nozzles. More specifically, the black nozzle array is placed such that it performs ink ejection in a scan line preceding that of the color nozzle arrays.
Since the black nozzle array and the color nozzle arrays are separately provided within a single head, however, it is difficult to miniaturize the inkjet head and further accurate positioning and high integration techniques are needed.
As another example of prior art, there has been disclosed an inkjet head in Japanese Patent Unexamined Publication No. 7-256874. This conventional inkjet head is provided with a plurality of arrays of nozzles wherein the upper half of a specific array is used for black ink and the respective lower halves of other arrays are used for different color inks; Yellow (Y), Magenta (M) and Cyan (Cy).
However, the lower half of the specific array and the respective upper halves of the other arrays are not used at all. Therefore, unused nozzles are easily clogged, resulting in deteriorated quality of printing.